This invention relates broadly to the signal processing art, and more specifically to a system of secure transmission of information. The invention also has its applicability in any field where a high-speed-data transmission is desirable. A long existing problem in the communication art has been the requirement for a high-speed-data-transmission system, which is as secure as possible, particularly where speech is the type of data being transmitted. Along with the requirement of speed and security, the received data must be as similar to the original, and hence as recognizable to the receiver of the information, as possible. It is the attempt to maximize the solution to the problems of speed, security and recognition that has been responsible for so much effort in the communication arts, particularly in the recent past. Recently, however, with the advent of and increased use of computers and sophisticated vocoders, the need for better solutions to these problems has been intensified. Typical efforts along this line are shown in U.S. Pat. Nos. 3,435,147 to Malm, and 3,488,445 to Chang. These patents are merely illustrative of the general effort in this area of technology and represent the most pertinent references the inventor has been able to discover. There are many other patents and publications which deal extensively with problems and various solutions in this particular area of data communications, particularly in the area of secure communications. The present invention represents a significant advance in the state-of-the-art over previous solutions to those problems mentioned and discussed above. The present invention significantly increases the speed and the security of data communications, while maintaining a high data recognition standard at the receiving end of the transmission.
This invention, moreover, is designed to utilize existing data communication links, in particular the existing telephone lines of the telephone system of the United States. By adjusting various parameters, the operation of the invention can be matched with the characteristics of the transmission line to provide a high-speed, secure and recognizable data transmission.